TESTING A HUMIC SPECIATION MODEL BY TITRATION OF COPPER-AMENDED NATURAL

Experiments were carried out in which samples of natural waters that had been acidified and amended with copper nitrate were titrated with base, and the activity of Cu z+ was monitored with an ion-specific electrode. The results could be explained in terms of the interactions of Cu 2+ with inorganic and organic ligands, as calculated using the Windermere Humic Aqueous Model (WHAM). Optimised fits were obtained by adjusting the concentration f"active " fulvic acid. The active fulvic acid represented about 80 % of the total concentration f dissolved organic matter for upland pools and lakes, and about 40 % for lowland rivers. 01998 Elsevier Science Lt